Structure and secretory activity of cultured chondrocytes from patients with osteoarthritis.

Cartilage samples were taken from OA patients in order to describe and quantify pro-inflammatory mediators. Samples were cultured under aseptic conditions in Dulbecco's modified Eagle medium at 37 degrees C for 10 days. Control samples, taken from non-inflammatory cartilage, were cultured under the same conditions. The levels of NO2- and NO3- were measured in the supernatant using a spectrophotometric assay. The activity of MMP-1 was quantified by ELISA. The concentration of NOx- was 47.3 +/- 4.1 mu M in the OA cartilague and 10.7 +/- 1.8 mu M in the controls. The average MMP-1 activity was 3,650 +/- 387 ng/ml in the OA cartilage and 2,150 +/- 190 ng/ml in the control samples. These increased values of MMP-1 and NOx- observed in the OA cartilage suggest a higher catabolic activity. A morphological analysis of OA chondral tissue using light microscopy shows that the surface of the tissue is characterized by the presence of aggregated chondrocytes or "clones" but in the deeper areas isolated cells are found. These results could be a significant contribution towards the identification of biological markers indicating the presence of OA activity.